Tuning coil shifter



' Au8 23, 1932 c. M. MURDocK 1,873,658

TUNING COIL SHIFTER Filed Nov. 24. 1931 2 sheets-sheet 1 a iiiiinnmunn Aug. 23, 1932. c. M. MuRDocK TUNING COIL SHIFTER Filed Nov. 24. 1951 2 Sheets-Sheet 2 v 1 a6 MMum-fw,

INVENTOR BY emrn.

ATTOR N EY f band of frequencies from Patented Aug. 23, 1932 UNITED sTATEs PATENT or-FlcE l CHARLES M. MUBDOCK, 0F MAYWOOD, CALIFORNIA TUNING coIL snIF'rEB Application led November`24, 1931. Serial No. 577,121. R S S The object of the invention is to provide a device adapted to hold a full set of the conventional interchangeable coils employed asv tuners in radio apparatus vto'cover the full the low wave, through the .broadcast band and above the latter, so that the desired coil may be immediately put in circuit by means exposed on the panel of the receiver; to provide a construction for interchangeable coils that will permit the inclusion of a selected one in circuit with the same length of leads as any other one, so that there may not be the disadvantages resulting from switching arrangement such as Where the coils are cut into and out of circuit by the manipulation of the switch; to provide a device of the nature described in which there will be indicated on the front ofthe dial the particular coil in circuit; to provide a construction that Will insure the retention of the selected coil in its proper position; to provide a contacting device that will insure firm contact with the terminals of the coil connected in circuit; and to provide generally a device of this nature Which is of simple form, of a character that may be manufactured at moderate expense, and of a construction susceptible of incorporation in conventional radio apparatus without material modification thereo With this object in view, the invention consists in a construction and combination of `parts of which a preferred embodiment is illustrated in the accompan ing drawings, but to which embodiment t e invention is not to be restricted. Continued use in practice may suggest certain changes or alterations and the right is claimed to make any change falling within the scope of the appended claims.

In the drawings: I e

Figure 1 is a side elevational view of the invention, the base and panel of the connected instrument being shown in section, as Well as certain other parts.

Figure 2 is a top plan view of the structure of Figure 1.

Figure 3 is a bottom plan view of the structure of Figure 1, the panel being shown in section.

Figure 4 is a sectional view on theplane indicated by the line 4-4 of Figure 1.

Instead of a plurality ofditferent coils for selective insertion in a receiving socket, or a multi le switch positionable to include any one o a plurality of tuning coils in circuit, the invention provides for mountin of the coils employed on a single movable ta le, such as that indicated at 10.- Movement of the table 10 is designed to accomplish the conso nection in circuit of any one of the coils 11 which are wound for different wave lengths, so that the short wave, broadcast and higher bands may be covered. Movement of the table in the illustrated embodiment is accom- 05 plished by rotation, the table having a king pin 12 journalled in a support 14, the latter eing mounted on the base 15 of the radio apparatus and having a bracket portion 16 1n which is journalled a shaft 17, the latter be- 7o ing disposed below the plane of the table and also having a bearing in the front panel 19, exterior to which the shaft is provided with a finger knob'20 by means of which it may be rotated.

The shaft 17 constitutes actuating means for the table and to this end is provided on one extremity with a beveled gear 21, the latter meshing with a beveled gear 22 mounted on theunder face of the table concentricalso ly with the king pin 12.

In the illustrated embodiment the coils 11 shown are of the detachable type and to provide for their being mounted on the table 10, the,` latter is rovided with of sockets 23, pre era'bly, but not necessarily, spaced at uniform an ular distances around t e table. The table eing of insulated material, the sockets are secured to the table as by cap screws 24, these cap screws passing a0 through the table and threading into the socketin the coil pin receiving holes of the latter. The cap screws thus serve as contact members on the under face of the table, by reason of being connected with the pin re- 95 ceiving hole of the socket, so that one terminal of'each Winding on the coil is electrically connected with one of the cap screws 24.

Instead of sockets 23, the coils may be permanently attached to the table with oom- 100 a plurality bined contacting and securing means such as the cap screws 24.

None of the coils 11 is in circuit until the table is so positioned for the contact member 2410i any coil to be positioned above the spring impelled contact members 25 which are carried by a yieldingly mounted insulating plate 26. The plate 26 is hingedly connected, as indicated at 27, with the support 14 and rests upon a compression spring 28 seated at one end on the arm 29 extending from the support 14. The spring thus serves to raise the plate 26 but the height it may be elevated is determined by the head of the stop screw 30 which passes through the free end of the plate and is provided with clamp nuts 31 above andbelow the plate.

When the contact members 24 of any coil are in position to engage the contact members 25 of the plate the head'of the stop screw 30 engages in a seat 32 on the under face of the plate, there being a seat properly positioned with respect to each coil, so that the table may be retained in circuit engaging position for any coil.

The contact members 25 consist of headed studs slidably mounted in bushings 34 which are in turn mounted in the plate 26. Each contact member 25 is individually yieldingly mounted by reason of a compression spring 35 compressed between its head and the upper face of its attendant bushing.

Each bushing has secured thereto a lug 36 by which connection may be made to appro priate parts of the radio apparatus by means of pigtail or other iiexible conductors.

In operating the invent-ion, rotation of the handle 20 serves to rotate the table 10 and angular movement imparted to the table results in depressing .the plate 26 by reason of the head of the stop screw being then disengaged from its seat- 32, after which the head of the screw slides against the under face of the table in the angular movement of the latter. Depression ot the plate 26,|a1so permits the Contact members 24 being disengaged from the contact members 25 and the coil which had previously been connected in circuit is thus disconnected and another connected in its place when the table is brought to rest with the stop screw engaging the seat 32 associated with the selected coil.

To provide for the operator or user being able to determine visibly what particular coil 1s 1n circuit, the table is surrounded with an tacts for connection in the circuit of a radio apparatus, and means for effecting movement of the table to selectively position any of the coils over said stationary member with its terminals in end engagement with the contacts of the latter, the stationary' member having a spring yieldingly impelling it toward the table.

2. A coil shift-ing device comprising a movable table, a plurality of coils carried on said table, a stationary member having contacts for connection in the circuit of a radio apparatus, and means foretiecting movement of the table to selectivelyv position any of the lcoils over said stationary member with its terlninals in end engagement with the contacts of the latter, the stationary member having a spring yieldingly impelling it toward the table, and the latching means consist-ing of a stop carried by said member and engageable with seats inthe under face of the table.

3. A coil shifting device comprising a movable table, a plurality of coils carried on said table, a stationary member having contacts for connection in the circuit of a radio apparatus, and means for eecting movement of the table to selectively position any of the coils over said stationary member with its terminals in end engagement with the contacts of the latter, the stationary member having a spring yieldingly impelling it toward the table, and the latching means consisting of a sto carried by said member and engageable witI-h seats in the under face of the table, and the contacts carried by said member being each spring impelled to render them individually yieldable.

In testimon -whereof I aiiix my signature.

C LES M. MURDOCK.

annular strip 37, this constituting a drum i on the peripheral face of which may be inscribed indicia visible through a window 35 and indicating to the operator the particular coil in circuit.

The invention having been described, what is claimed as new and useful is:

1. A coil shifting device comprising a movable table, a plurality of coils carried on said table, a stationary member having con- 

